Air-cooled retort



H. E. PRESTON AIR COOLED RETORT July 3, 1934.

5 Sheets-Sheet 1 Filed March 6, 1931;

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H. E. PRESTON AIR COOLED RETORT July 3, 1934.

5 Sheets-Sheet 2 Filed March 6, .1951

ZLL TZJ H E. PRESTON AIR COOLED RETORT July 3, 1934.

Filed March 6, 1931 5 Sheets-Sheet 3 I l l I 'L l fi l 5 H A a July 3, 1934.

H. E. PRESTON AIR COOLED RETORT 5 Sheets-Sheet 4 Filed March 6, 1931 jwcruior" Eu v.

July 3, 1934.

H. E. PRESTON AIR COOLED RETORT Filed March 6, 1951 5 Sheets-Sheet 5 Patented July 3, 1934 UNITED STATES PATENT OFFICE Application March 6, 1931, Serial No. 520,637

7 Claims.

This invention relates to improvements in mechanical stokers, and more particularly to underfeed stokers of the multiple retort type in which the fuel-supporting structure comprises alternately arranged tuyres and retorts and in which the fuel is fed through the medium of rams or pushers located in the bottoms of said retorts.

While having a particular application to stokers of the stated type, the invention in its broader aspects is applicable to retorts in general, and particularly to retorts wherein combustion air is fed to the fuel-bed past the outer surfaces of the retort walls.

In furnace stokers of the stated type, the use of highly preheated combustion air and high boiler ratings has resulted in a tendency of the sides of the retorts to burn, with consequent necessity for frequent replacements, and it is a principal object of the present invention to provide novel means for preventing such burnouts.

Another object of the invention is to provide novel means for utilizing combustion air for cooling the walls of the retorts to prevent damage of the latter by burning.

Still more specifically, an object of the invention is to provide in a stoker of the stated type a novel structural element constituting both a portion of the retort wall and a support for the tuyres, and comprising means for utilizing the cooling effect of the combustion'air passing to the tu'yres for the purpose of maintaining the said element at a reasonably low temperature.

The invention further resides in the provision, in conjunction with stoker elements of the character set forth, of novel means for preventing passage of any substantial quantity of combustion air through the walls and bottoms of the retorts, said latter means functioning in conjunction with the cooling means to materially prolong the life of the related stoker parts, as hereinafter set forth.

The invention further resides in certain novel structural details and arrangements hereinafter described and illustrated in the attached drawings, in which:

Figure 1 is a more or less diagrammatic elevational view showing the inner face of a side wall of a stoker retort made in accordance with my invention;

Fig. 2 is a plan view of the wall structure shown in Fig. 1; v

Fig. 3 is a fragmentary vertical sectional view through a stoker made in accordance with my invention showing the relative arrangement of tuyeres and retorts and illustrating details of my invention;

Fig. 4 is a face view of an upper retort side plate made in accordance with my invention;

Fig. 5 is a plan view of the plate shown in Fig. 4;

Fig. 6 is a view of the lower edge of the plate;

Fig. '7 is a face view of one of the intermediate side plates of a stoker retort structure made in accordance with my invention;

Fig. 8 is a plan view of the plate shown in Fig. 7;

Fig. 9 is an end edge View of the plate;

Fig. 10 is a face view of a bottom stoker retort side plate made in accordance with my invention;

Fig. 11 is a fragmentary plan view of the plate shown in Fig. 10;

Fig. 12 is an upper edge view of the plate;

Fig. 13 is an enlarged face view showing the joint between the ends of two of said side plates;

Fig. 14 is a section on the line 14-14, Fig. 13, 76 and Fig. 15 is a plan view of that portion of the retort wall illustrated in Fig. 13.

With reference to the drawings, and more particularly to Figs. 1, 2 and 3 thereof, a well known 80 type of stoker to which my invention applies comprises a plurality of inclined steel beams 1 constituting the supporting framework of the fuelsupporting portion of the stoker structure, these beams defining the sides of alternately arranged tuyeres and retorts, said tuyeres and retorts being designated in Fig. 3 by the reference numerals 2 and 3 respectively. Mounted at the upper edges of each of the beams 1 is a series of plates designated generally by the reference numeral 4, these plates being assembled in end-abutting relation, as shown in Fig. 1, and projecting above the upper edges of the beams 1 to form in efiect an extension of the latter. The plates 4 on the retort sides of the beams 1 overlap or extend downwardly below the upper edges of the said beams, the plates being so formed as to present on their retort sides smooth and flat surfaces which constitute the effective upper side wall surfaces of the retorts. Dead plates 5 are secured to and extend between the beams 1 within the retort spaces, these plates forming in the present instance supports for the fuel-feeding elements or pushers 6 which are adapted to reciprocate in the bottoms of the retorts and with the latter constituting the bottom walls of the retorts. The dead plates 5 are substantially horizontal, and the spaces in the side walls of the retort between the lower edges of the plates 4 and the tops of the dead plates are filled in by means of extension plates '7, the outer faces of which are flush with the corresponding faces of the plates 4 and form with the latter and as previously set forth the smooth side walls of the retorts between which the pushers operate.

As shown in Fig. 3, the assembly of plates 4 in addition to forming the side walls of the retorts also constitute a support for tuyere blocks or plates 8, which bridge the tops of the tuyre chambers 2 and are formed to provide the ports or openings (not shown) through which the combustion air is directed into the fuel-bed. For this purpose, the space below the beams I normally constitutes an air chamber, from which air under pressure passes freely to the tuyere chambers 2, and through the tuyere blocks 8 to the fuel-bed.

As further illustrated in Fig. 3, each of the plates 4 has at one side a projecting flange 11 which bears upon an upper edge of the beams 1, and the plates are secured to the beams by means of bolts 12. Means is also provided for securing the plates 4 together at their abutting edges, this connecting means being illustrated in Figs. 13, 14 and 15. The plates are provided in those faces thereof which form the inner wall surfaces of the retorts with countersunk recesses 13 which receive the heads of studs 14 which pass through the plates and are threaded into bars 15 which overlie the joint on the opposite faces of the plates. The countersunk recesses receive a suitable refractory material which covers the heads of the studs and protects them from the effects of the high retort temperatures. At the extreme sides of the stoker structure, plates 16 are provided which are secured to the adjacent members 15 through the medium of studs 17, the plates 16 constituting a support for the tuyere blocks of the terminal tuyeres.

Preferably, provision is made in accordance with the principles set forth in my co-pending application Serial Number 507,227, filed January '7, 1931, for sealing the retorts against influx of air from the air chamber so that substantially all of the combustion air passing to the fuel-bed is confined to the tuyeres, and in the attached drawings, I have illustrated means for sealing the joints between the adjacent ends of the various plates 4 and between the plates and the side beams 1. Thus, the abutting ends of the plates 4 are provided with recesses 18 and 19 forming cavities for reception of a suitable packing material 21, and a gasket 22 is inserted between the member 15 and the plates 4 so as to effectively seal the underlying portions of the joint. Recesses 23, 24, 25, 26 and 2'? are also provided in the plates 4, the extension plate '7, and the dead plates 5 for reception of packing 28, as illustrated, for sealing the joints between these plates and the beams 1; and in accordance with the invention described in my aforesaid copending application, means is also provided for sealing the joints between the pushers and the dead plates 5 and between the pushers and the walls of the retort constituted by the plates 4 and extension plates 7.

In accordance with my present invention, I provide each of the plates 4 with a fin structure designated generally by the reference numeral 31, which projects into the adjoining tuyere chamber, as illustrated in Figs. 3 and 14,. and around which the combustion air passing through the tuyeres to the fuel-bed circulates. These fins function to conduct heat from the wall-forming portions of the plates 4, which heat is withdrawn by the circulating air to effect a material cooling of the walls of the retorts and to maintain the walls below a predetermined maximum temperature where destructive heat action may occur.

The actual formation of the various plates 4 is illustrated in the views embraced by Figs. 4 to 12, inclusive. As therein illustrated, each of the plates is provided with a series of transversely extending upright fins 32, 32, the lower portions of the outer edges of which are connected through the medium of a web 33 so as to form in effect a series of fiues 34 between the fins 32 through which the combustion air in its normal movement through the tuyres may pass. The web 33 inclines at the top towards the body of the plate 4 and has the effect of deflecting the air inwardly against the inner surface of the plate proper as well as bringing it into intimate contact with the fins 32. Also by reason of the said inclination of the web 33, the flues are relatively restricted at their upper ends, which tends to increase the velocity of the air passing therethrough with a subsequent increased cooling effect. It will be noted by reference to Fig. 3 that in the present instance the lower projecting portions of the fins 32 of the adjacent pair of plates lie in close proximity to each other so that substantially the entire width of the associated tuyere chamber is embraced by the lower ends of the two sets of fiues. This provides that substantially the entire volume of air passing through the tuyeres shall flow through the fiues 34.

It will be apparent that by the aforedescribed invention I have provided a highly practicable and eflicient method of cooling the walls of the retorts of furnace stokers of the aforementioned multiple-retort type utilizing the combustion air in its normal passage to the tuyeres as the cooling medium.

Air cooling as described above in conjunction with the means, also described, for preventing combustion air from entering the sides or bottoms of the retorts effectively prevents burning of the retort walls under normal operating conditions, and in this respect meets the exacting requirements of the use in stokers of preheated combustion air and the present tendency toward high boiler ratings.

I claim:

1. A mechanical stoker, comprising a fuel supporting section, consisting of alternately arranged tuyere chambers and retorts, spaced walls defining said tuyere chambers and retorts, a plurality of fins projecting from the opposed faces of said walls into the tuyre chambers, said fins terminating at their ends adjacent the center of said tuyere chambers, webs extending between the fins projecting from each wall, said webs inclining upwardly toward their respective walls and forming with the fins flues adapted to conduct combustion air passing upwardly through said tuyere chambers against said retort walls.

2. A mechanical stoker, comprising, a fuel supporting section consisting of alternately arranged tuyere chambers and retorts, spaced walls defining said tuyere chambers and retorts, a plurality of fins projecting from the opposed faces of the said walls defining the tuyere chambers, tuyere blocks supported upon the walls of said tuyere chambers, and webs extendingbetween the fins on each wall and forming therewith fiues for combustion air passing upwardly through the tuyere chambers, said webs being inclined toward the walls in the direction of movement of said combustion air through the tuyre chambers,

whereby the air is deflected against the walls of the retorts.

3. A furnace stoker, comprising, a fuel supporting section, consisting of alternately arranged tuyere chambers and retorts, walls defining said tuyere chambers and retorts, tuyere blocks supported upon the walls of said tuyere chambers, extensions projecting into the tuyre chambers from the opposed faces of said walls, means provided on said extensions forming fiues open at the bottom to admit combustion air passing upwardly through the tuyre chambers, the upper open end of said flues being of lesser area than the bottom opening to form a restriction increasing the velocity of flow of said air past the walls of the retorts.

4. In a stoker, a fuel supporting section consisting of alternately arranged tuyre chambers and retorts, spaced walls defining said tuyere chambers and retorts, said walls comprising a plurality of beams and removable plates secured to said beams, said plates constituting the effective Wall surfaces of said retorts, tuyere blocks supported upon said plates and bridging the tops of said tuyere chambers, a plurality of heat conducting extensions provided on said plates and extending into the interiors of the adjoining tuyere chamber, to substantially the center thereof, and webs connecting the fins extending from each plate, said webs inclining upwardly toward their respective plates, thereby forming with said extensions fiues for combustion air passing upwardly through the tuyere chambers.

5. In a device of the class described, a plate adapted to form a portion of the side walls of a stoker retort and tuyere chamber, one face of said plate presenting a substantially smooth surface, a plurality of substantially vertical extensions provided on the other face thereof intermediate its upper and lower edges, webs extending between said extensions and inclining toward the face of said plate, said webs forming with said extensions flues for draft air, and means provided along the upper edge of said plate for supporting tuyere blocks.

6. In a device of the class described, a plate adapted to constitute a portion of the side walls of a stoker retort and tuyre chamber, one face of said plate presenting a substantially smooth surface, a series of substantially triangular extensions provided on the other face of said plate intermediate the upper and lower edges thereof, and web members secured to said triangular extensions near the outer edges thereof.

7. An article of manufacture, consisting of a cast metal plate adapted to constitute a portion of the side walls of a stoker retort and tuyre chamber, one face of said plate presenting a substantially smooth surface, a series of substantially vertical fins projecting from the opposite 100 face of said plate intermediate the upper and lower edges thereof, webs extending between the outer edges of said fins, said webs inclining upwardly toward the face of said plate and forming with said fins flues for draft air, means pro- 105 vided along the upper edge of said plate adapted to support tuyre blocks, and means provided on said plate for supporting the same in operative position.

HERBERT E. PRESTON. 

